Method for rolling disks and a disk rolling mill for the practice of the method

ABSTRACT

APPARATUS FOR ROLLING STOCK INTO CONTOURED DISKS INCLUDING UPPER AND LOWER ROLLS HAVING DESIRED CONTOURS NEGATIVELY ON THE WORKING SURFACES THEREOF WHICH SURFACES ARE OBTUSE ANGLE CONICAL SURFACES WHEREIN THE UPPER ROLL IS TILTED FROM THE VERTICAL AN AMOUNT SUFFICIENT TO PROVIDE ENGAGEMENT BETWEEN THE TWO WORKING FACES ON ONE SIDE OF THE CONE ONLY. PRESSURE EXERTING MEANS IS SHOWN ADAPTED TO URGE THE WORKING SURFACES TOGETHER. METHOD OF USING THIS APPARATUS IS DESCRIBED.

Oct. 12, 1971 ULRYCH ,METHOD FOR ROLLING DISKS AND A DISK ROLLING MILLFOR THE PRACTICE OF THE METHOD 4 SheetsSheet 1 Filed June 28, 1968 I./EI&

14 \Y: 22 12 r9 2 I I 23 I if 4 .5

lnven/or 051D V/r vcA AT TOR N5 y;

Oct. 12, 1971 o. ULRYCH 3,611,111

METHOD FOR ROLLING DISKS AND A DISK ROLLING MILL FOR THE PRACTICE OF THEMETHOD Filed June 28, 1968 4 Sheets-Sheet I lnvenlor: Otto Ulr Y MW Ar-mama Oct. 12, 1971 o, ULRYCH 3,611,711

METHOD FOR ROLLING DISKS AND A DISK ROLLING MILL FOR THE PRACTICE OF THEMETHOD 7 Filed June 28. 1968 4 Sheets-Sheet 5 lnvenlor 0H0 Uhwck BY!WMyl' 4 5%.?

ATTORNEYS Oct. 12, 1971 O ULRYCH 3,611,711

.METHOD FOR ROLLING DISKS AND A DISK ROLLING MILL FOR THE PRACTICE OFTHE METHOD Filed June 28. 1968 4 Sheets-Sheet 4 In van/0r: 0&0 wmh =WW W7 ATTORN YS United States Patent O1 flee 3,611,771 Patented Oct. 12,1971 3 611,771 METHOD FOR ROLLING DISKS AND A DISK ROLLING MILL FOR THEPRACTICE OF THE METHOD Otto Ulrych, Dortmund-Horde, Germany, assignor toRheinstahl Wagner Werkzeugmaschinenfabrik m.b.H., Dortmund, GermanyFiled June 28, 1968, Ser. No. 740,873 Claims priority, applicationGermany, July 1, 1967,

Int. Cl. B21h 1/02 US. Cl. 72-84 19 Claims ABSTRACT OF THE DISCLOSUREApparatus for rolling stock into contoured disks including upper andlower rolls having desired contours negatively on the working surfacesthereof which surfaces are obtuse angle conical surfaces wherein theupper roll is tilted from the vertical an amount sufficient to provideengagement between the two working faces on one side of the cone only.Pressure exerting means is shown adapted to urge the working surfacestogether. Method of using this apparatus is described.

The invention relates to a method of rolling disks that are to be shapedon both sides, especially thin-wall disks, and a disk rolling mill forthe practice of the method.

In the manufacture of wheel bodies and other diskshaped workpieces bythe rolling method, one normally begins with a previously formed blank,especially a forged blank, which is given the desired final shape on adisk rolling mill by the action of a plurality of rolls which modify thediameter and thickness of the blank. One known design of disk rollingmills for rolling previously forged blanks has rollers which are shortin proportion to the disk diameter, usually tapered, and arranged inpairs, and which are urged against one another during the rolling inorder to reduce the thickness of the blank and increase its diameter.The rolls are ifiISt applied in the vicinity of the hub of the disk and,for the purpose of rolling the disk web, they are displaced radiallyoutward and made to approach one another axially. Additional rolls orpairs of rolls are provided for the rolling and shaping of the rim andtread of the disk.

For the rolling of forged disks which undergo a relatively smalldiameter increase in the rolling process, as

in the case of wheel disks and railroad car wheels, dis-k rolling millsare used in which the pair of rolls acting on the disk from both sidesare short in proportion to the disk diameter and can be brought to bearagainst one another,

and they can simultaneously apply pressure radially of the disk. In thisrolling mill, the application of appropriately shaped tapered rolls inconjunction with a roll acting on the external periphery of the rim ofthe disk produces a reduction of the radial thickness of the rim and areduction of the thickness of the web, while at the same time increasingthe diameter of the disk. In this case, too, additional pairs of rollscan be provided for rolling down or maintaining the flanks of the 'rimof the disk.

The above mentioned disk rolling mills require preshaped blanks, and, onaccount of the nature of the rolling process which they permit, they canonly make disks having a flat web. This is because of the fact that thegap formed between the rolls engages the disk along only a portion ofits diameter, and shifts radially in relation to the center of the diskduring the rolling process.

A disk rolling mill has become known in which the one roll contains acomplete negative of the one side of the disk to be rolled, While thenegative of the other side is created on the mantle surface of anobtuseangle cone forming the counter-roll. The axes of the two rolls areset at an angle to one another. One roll is freely rotatable and theother is driven and they can be brought to bear against one another. Therolling process is performed as follows: a socket punched in one face ofthe disk is placed on a stud in the non-conical roll; the rolls are thenrotated and the gap between them is narrowed, increasing the diameter ofthe blank and rolling it into the negative of the non-conical roll. Withrolling mills of this kind it is possible to roll disks having a webthat is other than flat or one that has a special cross section.However, they have the disadvantage that the workpiece is lying fully onthe non-conical roll and is considerably cooled thereby. Consequently,this method and therefore this apparatus are unsuitable for the rollingof thin disks, especially those made of materials having a narrow rangeof suitable rolling temperature, or those which require a long rollingtime on account of their poor rolling characteristics.

It is an object of this invention to provide a novel means for rollingstock to a desired contoured shape.

Another object of this invention is to provide a novel rolling mill.

Other and additional objects of this invention will become apparent froma consideration of this entire specification including the claims anddrawing hereof.

In accord with and fulfilling these objects, one aspect of thisinvention includes a novel rolling mill which has an upper and lowerroll having a lower and an upper working face, respectively, whichworking faces are obtuse angle cones, and which rolls are angularlyoriented with respect to each other so as to have an obtuse anglebetween the axes thereof, preferably such that only a small portion ofthe conical working faces are in working relation to each other at anygiven time.

The invention makes possible the economical manufacture of thin diskshaving special cross sections, the shape given to one face being able todiffer from that given to the other. It offers special advantages in theproduction of axially symmetrical, discoidal bodies from highlyheat-resistant, expensive materials that are difficult to shape, such asthose used, for example, in engines for aircraft and spacecraft. Theforming of such parts in presses would entail very great press forcesand consequently high machine costs, and forming them by machining alonewould be uneconomical on account of the poor machinability of thematerials and the excessive waste.

The advantages of the invention are due to the fact that, on the onehand, the workpiece contacts the two forming rolls only in the area of aroll gap, so that the heat losses are slight, and, on the other hand,the roll gap extends over the entire disk radius, thereby eliminatingthe shifting of the roll gap radially with reference to the center ofthe disk, which renders any special fashioning of the disk impossible.

According to the invention, a discoidal blank heated to forgingtemperature is centered on one patterned roll, and is first partiallygripped between this one roll, which bears on its obtusely conicalmantle surface the pattern that is to be rolled into the one face of thedisk, and the other roll, which bears on its obtusely conical surfacethe pattern that is to be rolled into the other face of the disk, theaxis of the latter roll being at an angle to the axis of the former,while the rolls are rotated and the distance between them is reduced,and then the blank is shaped so as to fill the roll gap resulting fromthe pattern and the distance between the rolls. In order to achieve aspecified outside diameter of the disk in the rolling process andthereby keep down the material losses in the later machining of therolled disks, it is further proposed that the outside diameter of thedisk be limited by a boundary surface or rim collar rising above thepatterned mantle surface of the roll and flaring outward toward theother roll. For the rolling of disks whose outside diameter is greaterthan that of the disk blank and in which a central hub bore isultimately to be made, the invention proposes that the discoidal blankhave a center hole punched in it and that it be centered by theengagement of this hole With a centering stud provided on at least oneof the rolls. If, however, unperforated disks are to be produced havingan outside diameter larger than that of the blank, the discoidal blankis to have a central stud, according to the invention, and is to becentered by the engagement of this stud in a center recess in the roll.A simple blank manufacture and a reliable centering of the blank can beachieved by making the central stud of the blank and the recess in theroll cup-shaped. The use of punched or unpunched blanks having anoutside diameter equal to that of the punched disk is made possible bythe invention owing to the fact that the discoidal blank is centered byits outside diameter in the boundary surface of the roll.

In order to achieve the desired flow of material, especially in the caseof hard-to-form materials and deep patterns to be rolled into the disks,and in order to keep the roll wear low, it is furthermore proposed thatthe rolling be performed successively between a series of pairs ofrolls, each pair bringing the disk closer to the desired final shape,and the last pair having a pattern corresponding to the final shape.

For convenience in handling the workpieces, and to enable the equipmentto be installed in a smaller amount of space, particularly formulti-stage rolling, the invention proposes, as a disk rolling mill forthe practice of the method of the invention, a bottom roll having aperpendicular shaft and an upper roll having an axis at an angle to theperpendicular. An especially simple construction of the disk rollingmill can be achieved if, according to a further proposal, both rolls canbe driven and the upper roll can be brought to bear against the lowerone. To permit the achievement of optimum rolling conditions for variousdisk materials and diameters, it is desirable to provide for variationof the speed at which the rolls are driven. To enable equal rollingeffects to be achieved on both sides of the disk, and to enable thedistance between the unheld portion of the disk and the upper and lowerrolls to be small and equal in the interest of a secure disk guidance,the apex angles of the patterned mantle surfaces of both rolls are to beequal and as large as possible, preferably about 170. A roll gap that isparallel with reference to the theoretical, unpatterned mantle surfacesis produced by tilting the axis of the upper roll away from theperpendicular by an angle amounting to half of the difference betweenthe sum of the apex angles of the mantle surface of both rolls and 360.To permit an unstrained application of the upper roll to the lower, itis proposed that the direction of application of the upper roll againstthe lower be inclined from the perpendicular so that the angle ofinclination amounts to half of the difference between the apex angle ofthe lower roll mantle surface and 180, being thus perpendicular to theroll gap, and so that the intersection of the two roll axes lies alwaysin the center plane of the rolled disk. In order to keep the forcerequired for the application of the upper roll to the lower as small aspossible, thereby minimizing its adverse effects, particularly on themounting and guiding means of the upper roll, the force (rolling force)by which the upper roll is applied to the lower roll (or the resultantforce where more than one force is at work) and the resulting of therolling resistance acting in the area of the roll gap do not produce anymoment during the rolling process. This is achieved pursuant to theinvention by the fact that the line of application of the force by whichthe upper roll is applied to the lower roll runs in the direction ofapplication of the upper roll, and hence perpendicularly to the rollgap, and runs through or near the centroid of the rolling zone adjacentthe roll gap formed by the upper roll and the lower roll.

The convenient internal centering of the pre-punched disk on the lowerroll with the production of only a small burr or fin in the area of thehole is achieved according to a further proposal by means of a taperedcentering pin in each of the rolls, projecting from the center of eachroll, the sum of the projecting lengths of the centering pins beingsmaller than the thickness of the rolled disk in the area of thecentering pins.

Lastly, the rim collar mounted on the lower roll and forming the outsideboundary of the roll gap is removable so as to permit the easy removalof the rolled disk by means of a fork lift truck or the like.

Understanding of this invention will be facilitated by reference to thedrawing in which:

FIG. 1 shows a longitudinal section through a disk rolling mill with adisk in the final phase of the rolling;

FIG. 2 shows a partial section through the upper portion of the diskrolling mill on line AB of FIG. 1;

FIG. 3 is a top view of the disk rolling mill;

FIG. 4 shows a forged and punched blank;

FIG. 5 shows tolls of the disk rolling mill in the rolling position witha disk rolled from the blank of FIG. 4;

FIG. 6 shows a forged, unperforated blank having a hemisphericalcentering boss;

FIG. 7 shows tools of the disk rolling mill in the rolling position witha disk rolled from the blank of FIG. 6;

FIG. 8 shows a forged and punched blank;

FIG. 9 shows tools of the disk rolling mill in the rolling positionroughing the blank of FIG. 8;

FIG. 10 shows the roughed blank produced as shown in FIG. 9; and

FIG. 11 shows tools of the disk rolling mill in the rolling positionwith a disk rolled from the roughed blank of FIG. 10.

In a rolling mill frame 1, a lower roll holder 2 is rotatably mounted ona hydrostatic thrust bearing 3 and two shaft bearings 4 and 5 with avertical shaft 6, and is driven through a gear transmission 7 and apartially shown drive shaft 8 by a variable-speed motor which is notrepresented. An upright 9 of the rolling mill frame 1 has guideways 10which are inclined 3.5 from the vertical and on which a slide 11 isdisplaceably guided. An upper roll holder 12 is rotatably mounted on theslide 11 on a hydrostatic thrust bearing 13 and two shaft bearings 14,15, with a shaft 16 inclined 7 from the vertical, and it can be driventhrough a gear transmission 17 by a variable-speed motor 18. Motor 18runs synchronously with the motor driving shaft 8, as a result of beingpowered by a common Ward-Leonard system. Two plungers 19 are fastened tothe top of the slide 11. The plungers 19 are held in two double-actinghydraulic cylinders 20 fastened to the upright 9. The large upper pistonfaces and the small lower piston faces of the plungers 19 can be drivenby hydraulic fluid by means of a hydraulic control 21, which is notshown in detail.

The plungers 19 and hydraulic cylinders 20 are so arranged that the lineof application of their resultant force lies in the plane passingthrough the perpendicular shaft 6 and the inclined shaft 16, is inclined3.5 from the vertical, and runs approximately through the centroid ofthe rolling zone which is to be explained later.

A lower roll 23, 23', 23" and 23", respectively, is fastened to a toolplate 22 of the bottom roll holder 2 by known means. Its top side 24(FIG. 7) is of conical construction with an apex angle of 173 and bearsthe pattern that is to be rolled into the bottom side of a disk 26, 26,26" and 26", respectively. The bottom rolls 23, 23', 23 and 23" are eachshaped according to the desired disk design. The bottom roll 23 (FIG. 7)has a central hemispherical recess 27. The bottom rolls 23, 23" and 23"(FIGS. 5, 9, 11) are each provided with a centering pin 23, 28", 28fastened, by means not shown, in a center bore. The centering pins havea central cup 29 and have a taper at the end that projects from thebottom roll. A rim collar 32 is removably mounted on a tapered portion30 and a flange 31 on the outer periphcry of the bottom rolls 23, 23',23" and 23', and projects above the bottom roll. The inner surface 33 ofthe rim collar 32 flares comically in'the portion that is free of thebottom roll, at an angle corresponding to the direction of the guideway10.

' A top roll 35, 35', 35", 35', respectively, is fastened removably to atool plate 34 of the upper roll holder 12 by means which are not shown.A bottom face 36 (FIG. 7) of the top roll is of conical shape with anapex angle 37 of 173, and it bears the pattern that is to be rolled intothe top side of disk 26, 26, 26" and 26", respectively. The upper rolls35, 35" and 35" are provided with a center bore into which a centeringpin 38, 38" and 38", respectively, of the same design as the centeringpin 28, 28" and 28", respectively, is inserted and fastened. At thepoint of the shortest distance between the bottom roll and the top ,rollis a roll gap 39. When both rolls are in contact with the disk 26, 26',26" and 26', respectively, a rolling zone is formed here, which in theperipheral direction of the roll has the shape of a narrow segment orsector of a circle. Approximately through the centroid of this rollingzone runs the line of the application of the resultant force of theplunger 19 driven by hydraulic fluid, as already mentioned above.

A forged and punched blank 40 from which disk 26 is made is shown inFIG. 4. By rolling the blank between rolls 23 and 35 a disk is producedbearing the pattern shown in 'FIG. 5. The point of division of flow inthis disk, i.e., the point at which the zone in which the material flowsradially inward during the rolling meets the zone in which the materialflows radially outward during the rolling, is identified by a line 41.The forged blank 40', which is provided with a hemispherical boss 42 inthe center as shown in FIG. 6, will be made into the disk 26' by rollingbetween the rolls 23' and 35 bearing the pattern shown in FIG. 7. Theforged and punched blank 40" of FIG. 8 is roughed between the rolls 23"and 35" of FIG. 9 to a disk 26" which is finish-rolled between the rolls23" and 35" of FIG. 11 to form a disk 26".

The procedure is as follows:

In order to produce a disk 26 according to FIG. 5, one starts with aforged and punched blank 40. This blank is of such dimensions and shapethat, on the one hand, a minimum of forming under the forging press isrequired, and on the other hand the distribution of material in it comesas close as possible to the material distribution in the rolled disk 26,taking into consideration the point of division of flow 41 establishedby the area of maximum material accumulation in the rolled disk. Theblank 40 is punched to fit the centering pin 28. The slide 11 of therolling mill is in its upper end position. Rolls 23 and 35 are standingstill. The blank 40, heated to forging temperature, is laid on the lowerroll 23 and centered by its hole on the centering pin 28. The blank lieshorizontally. When the hydraulic control 21 is set to Advance, slide 11is lowered until the upper roll 35 settles on blank 40 and brings itinto a tilted position in a one-sided contact between rolls 35 and 23;,this tilt being determined by the apex angles 25 and 37 of the rolls andthe tilt of the upper roll axis 16. When the hydraulic control 21 isthen set to Roll, the hydraulic pressure required for the predeterminedrolling force is applied to the upper surfaces of plunger 19, and themotors driving rolls 23 and 35 are energized, thereby accelerating rollsand blank to the selected speed. The rotation of the rolls and theblank, with the simultaneous diminution of the distance between therolls under the influence of the rolling force brings about the gradualforming of blank 40 to disk 26 which has 'a shape conforming to the rollpattern. In this process the material outside of the line of division offlow flows substantially outward, where it is limited by the insidesurface 33 of the rim collar 32. The material inside of the line ofdivision of flow is displaced substantially inward, its flow beinglimited by the centering pns 28 and 38.

Owing to the tilted position of the disk during the rolling process,only a very small fraction of the disk surfaces are in contact with therolls. Most of the disk surfaces are free of the rolls, so that the lossof heat from the disk to the rolls is slight, even when the rolls areinternally cooled. As soon as the outside diameter of the diskencounters the rim collar 32, diameter increases ceases, because despitethe fact that most of the disk is unsupported, approximately two-thirdsof its exterior periphery remains within the inside surface 33 of therim ring 32. The continued downward feed of the upper roll in this phaseof the process merely produces a complete filling out of the patterndetermined by the roll gap 39 formed by lower roll 23, upper roll 35,centering pins 28 and 38 and rim ring 32. Any excess material penetratesinto the gap between the two centering pins and collects in cups 29 inthese pins.

The rolling speed, i.e., the rotatory speed of the rolls, and therolling force, i.e., the force applied to plunger 19, are selected onthe basis of the working characteristics of the material being rolled.In the case of hard-towork, highly heat-resistant materials, for whichthe method and apparatus are particularly well suited, a very slightreduction per revolution is made, at correspondingly high rolling speed.After completion of the rolling process the rolls are stopped, and slide111 is raised back to its upper terminal position by applying hydraulicpower to the lower piston faces of plunger 19. Rim ring 32 is liftedfrom the bottom roll 23', whereupon the entire periphery of the rolleddisk 26 will be caught in the rim ring and the disk will be lifted withthe ring out of the rolling mill. The disk can be removed from the rimring for further transportation, merely by inverting the ring or by someother such operation.

Depending on the final pattern desired in the disk, it can then befurther worked, or, if desired, it can be reheated, if necessary, androlled in stages in additional rolling mills. It is also possible toperform multi-stage rolling using only a single rolling mill by firstrolling a suitable number of disks, and then replacing the rolls withothers having the pattern required for the next rolling stage. I

An example of two-stage rolling is shown in FIGS. 8 to 11. In this caseone starts out with a forged, punched blank 40". This cylindricalperforation in blank 40" has a relatively large diameter to correspondto the material distribution in the finished disk 26". The blank is laidon the lower roll 23 and centered thereon by a centering pin 28". In thefirst rolling stage blank 40" is rolled between rolls 23" and 35 in themanner described previously, to form a disk 26". Since disk 26" at theend of the rolling already has the outside diameter of thefinishedrolled disk 26", the centering of disk 26" on bottom roll 23" inthe second rolling stage is performed by means of the inside surface 33of the rim ring 32. The rolling process in the second stage reduces theinside diameter of the disk to the size determined by centering pins 28"and 38".

If an unpunched disk is to be rolled whose blank diameter is smallerthan the diameter of the rolled disk, in the interest of reducing theforged work, a blank 40' is used which has a hemispherical centeringboss 42, as shown in 'FIG. 6. When this blank is laid on the bottom roll23' it is centered in the hemispherical recess 27 in the bottom roll.Otherwise the rolling process is the same as described before.

It is preferred in the practice of this invention to produce titaniumproducts in disk form. In this regard it has been found that titanium isperculiarly well-adapted to use and to shaping using the device andmethod of this invention. The disk should be rolled at a temperature ofabout 900 to 1040 0., preferably at least about 950 C. since it is onlybetween these temperatures that titanium can be economically rolled.Further it is preferred that the roll gap widen in a radially outwarddirection, whereby to ensure the flow of material radially outwardduring rolling of the titanium disks.

What is claimed is:

1. Method of producing contoured disks which comprises heating atitanium disk blank to 900 to 1,040 O; inserting such hot disk blankbetween two contoured rolls, which rolls have disk directed contouredconical surfaces with axes disposed at an angle to each other; andturning said rolls for a time sufficient and with a force sufficient toimpart said contour to said disk blank.

2. A roll mill comprising two oppositely disposed contour faced rollshaving a centering pin projecting from the center of each adapted tocontour a workpiece therebetween wherein each of said rolls has aworkpiece directed working face which is itself an obtuse angle conicalsurface having substantially the same apex angle and which face has anegative of the contour intended to be imparted to said workpiece, andwherein the axes of said rolls diverge from each other by an obtuseangle; which mill contains means to rotate both of said rolls about itsaxis, means to urge said working faces toward each other and meansdefining a peripheral boundary about said workpiece.

3. Mill as claimed in claim 1, wherein said rotation means is a variablespeed drive.

4. Mill as claimed in claim 1, wherein the apex angle 7 of the conicalsurfaces is about 170.

5. Mill as claimed in claim 1, wherein said roller axes divergenceobtuse angle is about twice the cone apex angle minus 180.

6. Mill as claimed in claim 1, wherein said means to urge said workingfaces together is applied along a line which diverges from the dividerof the angle 'y by about 90.

7. Mill as claimed in claim 6, wherein a roll gap exists betweenadjacent portions of said working faces and wherein said line of appliedurging is directed toward the center of said roll gap.

8. Mill as claimed in claim 7, wherein said roll gap widens in a radialdirection.

9. Mill as claimed in claim 7, wherein said line of urging issubstantially perpendicular to said roll gap.

10. Mill as claimed in claim 1, wherein the combined length of saidcentering pins is less than the desired thickness of the workpieceadjacent thereto.

11. Mill as claimed in claim 1, wherein each working face has adifferent contour.

12. Mill as claimed in claim 1, wherein said boundary surface flaresfrom one of said working faces to the other of said working faces.

13. Method as claimed in claim 1, including centrally prepunching saiddisk blank.

14. Method as claimed in claim 1, including forming a centrally disposedrecess in said disk blank and mounting said disk blank in said mill suchthat said recess mates with a projection from said working face.

15. Method as claimed in claim 1, including forming a centrally disposedprojection on said disk blank and mounting said disk blank in said millsuch that said projection mates with a recess in said working face.

16. Method as claimed in claim 1, carried out successively with aplurality of roll pairs.

17. Method as claimed in claim 1, including urging said working facestogether during operation of said rolls.

18. Method as claimed in claim 1, wherein said disk is at about 900 to950 C. during rolling.

19. Method as claimed in claim 1, including forcing said disk materialin an outward radial direction during said rolling.

References Cited UNITED STATES PATENTS 915,232 3/1909 Slick 7284 965,0397/1910 Slick 72-84 1,114,396 10/1914 Slick 72-84 1,306,262 6/1919Knowles 72--86 1,855,449 4/1932 Hughes 72-84 LOWELL A. LARSON, PrimaryExaminer U.S. Cl. X.R. 7286

